1. Technical Field
The present invention relates to power-consumption-reducing portable or stationary information devices; to a power-saving-mode switching method for reducing information device power consumption; and to a recording medium, such as a magnetic disk, an optical disk or semiconductor memory, in which a power-saving-mode switching program is stored.
2. Description of Related Art
In various electronic devices, there have been proposed various power control means for reducing the power consumption. Also, there has been known various power control means which supply the operating power to the electronic device without increasing the current capacity of a power supply by the suppression of a peak current. In particular, in the portable information device in which the power supply that supplies the operating power is comprised of a battery, in order to downsize and lighten the battery, or in order to elongate a continuous applicable duration of the battery, there have been proposed various structures including the power saving control function.
For example, FIG. 6 shows a schematic functional block diagram of a conventional example. A power mode control means 61 controls a power mode changing means 62 in accordance with a device use request, an interruption from a timer portion 65 at each set time, a temperature detection signal from the temperature detecting means 64, or the like, and changes over a voltage, a clock frequency or the like which is supplied to a component 63a such as a processor between a normal power mode and a low power consumption mode.
For example, in response to a request for using a device or the like, the power mode control means 61 controls the power mode changing means 62 and supplies a normal operating voltage and a clock signal of a normal clock frequency to the component 63a such as a processor so as to operate the component 63a as the normal power mode. Then, if there is no use request for a predetermined period of time or longer, any one or both of the supply voltage and the clock frequency are lowered, or the clock signal is stopped to set the mode to the low power consumption mode.
Further, the temperature of a component 63b such as a magnetic disk is detected by the temperature detecting means 64, and if the operating temperature rises over a set temperature, the power mode control means 61 controls the power mode changing means 62 and sets the component 63a such as a processor to the low power consumption mode, to thereby reduce the access frequency to the component 63b, thus suppressing the rise of the temperature.
Moreover, the timer portion 65 notifies the power mode control means 61 every set time and controls the power mode changing means 62 so as to change over between the low power consumption mode and the normal power mode. For example, as applied to portable telephones and the like, in a standby state where talking or data transmission/reception is not conducted, the mode can be changed over to the low power consumption mode, and can be changed over to the normal power mode which enables the reception detection, the position registration request and the like every set time by the timer portion 65.
In general, the power consumption in the low power consumption mode such as a standby state is under half the power consumption in the normal power mode where the device is in an active state. Accordingly, as the duration of the low power consumption mode is longer, the power consumption as a whole can be reduced. Further, as the storage device of the information device, a large-capacity storage device such as a magnetic disk device, a magneto-optical disk device or an optical disk device is applied. In addition, in order to improve the data transmission speed, a tendency is made to increase the rpm of a disk. Therefore, the capacity of a motor is also increased, and a start current is also increased for conducting a high-speed start.
Further, there has been known a control means which operates in such a manner that if there is no access to the above storage device for a given period of time or longer, the device is shifted from the active state to an idle state, if there is yet no access to the above storage device for a given period of time or longer, the device is shifted to the standby state, and if there is still yet no access to the above storage device for a given period of time or longer, the device is shifted to a sleep state, to thus gradually reduce the power consumption, and if there is an access, the device is shifted to the active state. In this case, for example, if the device is shifted from the sleep state to the active state, a motor that rotates the disk is started so that a large start current flows. In the case where the start current is supplied from a battery which is a power supply, in order to start the motor stably and at a high speed, it is necessary to select the battery of a current capacity which enables the supply of the start current.
Therefore, there has been proposed an information device having a power saving mode changing means shown in FIG. 7. In this case, the information device includes a processor (CPU) 71, a read only memory (ROM) 72, a dynamic random access memory (DRAM) 73 and a floppy disk device (FDD) 74 as a large-capacity storage device. The information device further includes an operation mode control circuit 76 for controlling those operation modes and a motor current detecting circuit 75 for detecting the current of a spindle motor of the floppy disk device 74. FIG. 7 shows the outline of a control path of the operation mode control circuit 76.
Upon reception of a spindle motor start command to the floppy disk device 74 from the processor 71, the operation mode control circuit 76 stops the clock signal of the processor 71 and sets the dynamic random access memory 73 to a self-refresh mode, and thereafter sends a spindle motor start signal to the floppy disk device 74.
In this case, most of the power consumption results from the spindle motor of the floppy disk device 74. Then, the spindle motor starts, and a current that flows in the spindle motor is detected by the motor current detecting circuit 75 and notified to the operation mode control circuit 76. The operation mode control circuit 76 starts to supply a clock signal to the processor 71 when the current that flows in the spindle motor is lowered to a set value or less, or after a set time elapses from the start of the spindle motor, and also returns the operation of the dynamic random access memory 73 to an original operation and sets the operation to the normal power mode. As a result, the peak of the current as a whole can be reduced (for example, refer to Japanese Patent Application Laid-Open No. 1996-221147).
In the case where the information device is of the portable type, the operation power supply is made up of a battery. In this case, as described above, the peak current supplied from the battery is suppressed so that a battery small in current capacity is applicable, as a result of which the battery can be downsized and lightened in weight. Alternatively, the applicable duration of the battery can be elongated. In order to conduct the power saving control, in the case where there is provided means for detecting the current of the spindle motor as in the above-mentioned conventional example, it is necessary to add a hardware such as a resistor as the current detecting means or a voltage detecting means for detecting a voltage between both ends of the resistor, resulting in such problems in that the mounting area increases and the costs increase. In addition, since the capacity or the like of the spindle motor is different for each of the kinds of information devices, it is necessary to change the current set value in accordance with the kind of the spindle motor. Thus, the means for suppressing the peak power leads to an increase in additional circuits, to thereby increase the costs.
In a magnetic disk device, a magneto-optical disk device or the like as the large-capacity storage device, in general, the start command of the spindle motor is generated not from a processor but from a firmware such as a magnetic disk device. In other words, a command for starting or stopping the spindle motor is generated by the firmware in accordance with an access request of the data read/write from the processor. The above-described conventional power saving control means of the information device with the floppy disk device cannot be applied to the above general structure.